SAN JOSE — A man’s body was discovered by a kayaker near the Alviso marina Saturday morning, but circumstances of the death were not immediately known, authorities said.

A kayaker on Coyote Creek about a mile east of the Alviso Slough encountered the body about 10:15 a.m. and called 911. The San Jose Fire Department dispatched two water-rescue boats and two all-terrain vehicles to meet the kayaker, while a Cal Fire helicopter watched overhead, said Fire Capt. Rob Brown.

Authorities secured the site while investigators and a dive team from the Santa Clara County Sheriff’s Office — which has jurisdiction — were summoned. They retrieved the body about 3:20 p.m. about 4 miles from the Alviso marina, near the border of Santa Clara and Alameda counties. The kayaker who made the discovery was questioned and released.

Sheriff’s Sgt. Kurtis Stenderup said Saturday afternoon that it was too early to determine whether foul play was involved in the death.

Brown said the area is “mostly accessible by water” and that the Cal Fire helicopter was the first to locate the kayaker and the body.

The Fire Department’s Urban Search-and-Rescue team was also called. Soon after reaching the site, team members confirmed that the man, for whom no other description was given, was dead. Brown said it was not immediately clear how he died or how long the body had been in the water.

Robert Salonga is a Pulitzer Prize-winning reporter covering crime and public safety for The Mercury News. A San Jose native, he attended UCLA and has a Master's degree in journalism from the University of Maryland. He previously reported in Washington, D.C., Salinas and the East Bay, and is a middling triathlete. Reach him the low-tech way at 408-920-5002.

Otto Warmbier was arrested in January 2016 at the end of a brief tourist visit to North Korea. He had been medically evacuated and was being treated at the University of Cincinnati Medical Center when he died at age 22.